ChemInform Abstract: 1,2‐Asymmetric Induction in Dianionic Functionalization Reactions of L‐Aspartic Acid Diesters.

Abstract

1,2-Asymmetric Induction in Dianionic FunctionalizationReactions of L-Aspartic Acid Diesters.-The functionalization of dianions derived from aspartic acid esters (I) with various electrophiles (II), (IX), and (XI) is studied. It is shown that the alkylation proceeds with moderate to high anti-selectivity in most cases which is probably due to the formation of a (Z)-lithium ester enolate intermediate. High levels in asymmetric induction are obtained when the alkylation is carried out at temperatures below -50 • C. The stereoselectivity can be reversed to syn-alkylation by increasing the steric bulk of the α-ester group [cf. compound (IVd)]. Reaction of triacid (V), derived from functionalization product (IIIa) by hydrolysis, with paraformaldehyde provides access to oxazolidone (VII), a key precursor of a potential peptidomimetic. -(PARR, IAN B.; DRIBBEN, ANTHONY B.; NORRIS, SIMON R.; HINDS, MARK G.; RICHARDS, NIGEL G.